The purpose of the proposed work for the following year is to define the genetic and microenvironmental regulations of histaminase and histamine methyl transferase synthesis and release from human leukocytes. These two proteins are the principle enzymes mediating the catabolism of histamine and therefore probably have an important role in modulating inflammation and/or physiological effects of histamine. The apparent inducability of eosinophil but not neutrophil histaminase in parasitic infestation warrants more detailed studies in experimental animals and with patients' leukocytes to define the mechanism of the induction and perhaps explore the potential for a diagnostic tool. BIBLIOGRAPHIC REFERENCES: Bhan, A.K., Grand, R.J., Colten, J.R., and Alper, C.A.: Liver in Alpha 1-Antitrypsin deficiency: Morphologic observations and in vitro synthesis of Alpha 1-Antitrypsin. Ped. Res. 10: 35-40, 1976. Alper, C.A., Colten, H.R., Gear, J.S.S., Rabson, A.R., and Rosen, F.S.: Homozygous human C3 deficiency: the role of C3 in antibody production, Cls-induced vasopermeability, and cobra venom-induced passive hemolysis. J. Clin. Invest. 57: 222-229, 1976.